Circuit breakers are used to protect circuits against many different types of electrical fault and overcurrent conditions. When a circuit breaker interrupts current to a circuit, it may be challenging for a person to troubleshoot the protected circuit without any knowledge about the interruption. As a consequence, some circuit breakers now incorporate user diagnostic features. One common diagnostic feature involves the use of Light-Emitting Diodes (LEDs) on the circuit breaker to indicate a reason why a circuit breaker tripped. The LEDs on the circuit breaker can be used to display a trip code, which indicates a particular type of fault condition. However, the use of LEDs has a drawback of adding cost and complexity to the circuit breaker.
Another circuit breaker diagnostic feature is described in U.S. Pat. No. 8,243,411 to Brett Larson (the “Larson patent”), entitled “Electronic Miniature Circuit Breaker With Trip Indication Using The Breaker Tripping Function As The Feedback Mechanism”. In one embodiment of the Larson patent, a circuit breaker is configured to convey diagnostic information, such as a type of fault condition, concerning a prior occurrence of a trip event by implementing a trip sequence (or indication) as a function of time during a read out operation. For example, an arc fault condition is indicated by having the circuit breaker trip after a certain time delay (e.g., the handle is moved to an ON position and then to the TRIPPED position after a delay of two seconds), and a ground fault condition is indicated by having the circuit breaker trip after another certain time delay (e.g., the handle is moved to an ON position and then to the TRIPPED position after a delay of four seconds), wherein contacts of the circuit breaker are closed in the ON position and are opened in the TRIPPED position.
While the diagnostic feature of the Larson patent does not result in any additional cost or add significant complexity to the circuit breaker, it may be difficult for some users to distinguish between different indication time periods of a trip sequence during a read out operation. The movement of the circuit breaker handle to the tripped position may also confuse users with little or no technical experience during the read out operation. Furthermore, by relying on human senses to determine an indication time period of the trip sequence during the read out operation, the circuit breaker is limited in a number of types of fault conditions conveyable as a function of time since humans cannot easily distinguish time periods that differ in the seconds to sub-second range.